Junie Is Shopping for Dinner

Junie is shopping for dinner. She notices that hamburgers are on sale, so she puts the hamburgers in her cart instead of the hot dogs she originally came to the store to buy. She then heads over to the bread aisle to pick up hamburger buns. The change in Junie's demand for hamburger buns is due to a change in:

A) the price of related goods.
B) Junie's income.
C) Junie's preferences.
D) Junie's expectation of future prices.